Refrigeration apparatus



June 1, 1937. E. s. PRIDHAM REFRIGERATION APPARATUS Original Filed May51, 1932 illlliilllllfllllllllllil!!! INVENTOR, EDWIN s. P/P/DHAM.

A TTORNE Y Patented June 1, 1937 2 032 755.

UNITED STATES PATENT OFFICE Edwin S. Pridham, Oakland, Calif.

Application May 31, 1932, Serial No. 614,322 Renewed January 15, 1935 5Claims. (01. 62-90) y invention at s to r f i atin appachanger. Heattransference from the liquid in ratus, and more specifically to suchapparatus in the circulating system is rapid due to the use of whichevaporation of a fluid at atmospheric presmetals having good heatconductivity in the heat sure produces the cooling effect. exchanger.

5 Among the objects of my invention are: To In Figure 1 a circulatingsystem I, preferably provide a system in which an efficient loss of heatbuilt up from pipe, has a cooling coil section 2, W111 occur; o p v m nfor provi ing a large and a heat exchange section 4. This forms a areaof evaporating surface; to provide a circuclosed system and is filledwith a liquid, preferlating refrigerating system in which the heatexably water or brine. The cooling coil is conchanger and cooler areseparate units; and to tained in a refrigerator box 5, which is provided10 provide a refrigeration system which is simple in with a removabletop cover 6. While I have construction, economical to'manufacture,durable shown a top opening box, it will be apparent that and efficientin use, and which permits of atthe cooling coil may be so arrangedinside the taining a low, humidity in the interior of the box that aside door can be used. The refrigerrefrigerator box. ator box ispreferably double walled and the space 15 Other objects of my inventionwill be apparent between the walls filled with a good heat inor will bespecifically pointed out in the descripsulator such as ground cork orasbestos wool. Box tion forming a part of this specification, but I legsl'serve to raise the cooling chamber from do not limit myself to theembodiment of my inthe floor.

vention herein described, as various forms may The heat exchange portionof the system is L0 be adopted within the scope of the claims.preferably a casting of a metal having high Referring to the drawing:heat conductivity such as copper or aluminum,

Figure 1 is a longitudinal sectional view of a and is preferablyprovided with integral fins 9 preferred type of my refrigeration system.as shown in Figure 2. The center of the heat ex- Figure 2 is a crosssectional view through the changer is preferably bored out to form aninte- 25 heat exchanger shown in Figure l on the line rior straight andsmooth tube l0. Couplings ll v and elbows l2 serve to connect thisstraight por- Figure 3 is a longitudinal sectional view of the tion tothe system I. Unions [4 are provided so top portion of an alternativeform of heat exthat the two units may be easily disconnected if changer.desired. 30

Figure 4 is a crosssectional view of the heat An alternative form ofheat exchanger is exchanger as shown in Figure 3, and taken on shown inFigure 4', and here thecentral bore is the line 4-4. connected to thehollow fins l5; These fins are The principle upon which the invention isprovided with seepage holes 16 of small diameter based is that ofcooling by the evaporation of at extending through the fin "walls andconnecting volatile fiuid. The degree of cooling will be dethe interiorof the heat exchanger with the outpendent upon the difference intemperature beside. f tween the wet and dry bulb thermometers, and Inboth forms of heat exchangers the fins are the device will be mostefficient in hot dry clicovered with absorbent fabric H such as coarse40 mates, where a cooler is most desirable. Crude linen, burlap orcanvas. When solid fins are used 40 forms of coolers using the aboveprinciple are holes I9 are preferably provided in the finstrucexemplified by the porous Mexican ollas for coolture to permit aircirculation through the fabing water, and the wet burlap mountain typeric. cooler which is well known in the art. The entire heat exchanger issurrounded by a Broadly speaking my inventionv comprises a casing 20which not only supports the structure, 45 circulating liquidrefrigeration system which is but acts as a flue to confine air to thespace ocdivided into two portions. One portion is on the cupied by theheat exchanger. The bottom porinterior of a chamber to be cooled, andthe tion 2| of this casing is preferably formed into other portion is aheat exchanger. This portion a cone shape and provided with a drain pipe22 of the system is provided with a convoluted surto carry offaccumulated unevaporated fluid. 50 face covered with fiuid absorbentmaterial and The bottom portion 2| of the casing may be this materialkept saturated with a volatile fluid. solid as shown, and air suppliedto the casing by The fluid is then evaporated rapidly by causing blower24, or, it may be perforated, and the draft a current of air to movepast the absorbed fluid of air created through the casing by chimney inthe fabric on the convolutions of the heat exaction. 55

A tank 25 smaller in diameter than the casing, is supported on the topof the casing 20 by brackets 26, and the bottom of the tank isperforated with small drip holes 21. A supply of volatile liquid,preferably water, on account of its availability and cheapness, isprovided by a faucet 28 in connection with the water main 29.

When the hollow fin form is used as shown in Figure 4, the tank 25 isnot perforated, but is connected directly to the circulating system asshown at 30. This allows water from the tank to supply the loss of waterthrough theseepage holes I 6 in the walls of the hollow fins I 5.

Casing 20 and cooperating structures are mounted on casing legs 3| whichserve to rais the heat exchange structures off the floor.

In operation water is admitted to the tank and drips onto the fabricmounted on the fins, and is absorbed by the fabric. The air movedthrough the casing either by draft or by the blower as shown, evaporatesthe absorbed water and the temperature of the fabric is reduced tothat'of the wet bulb thermometer. This fabric being in intimate contactwith a good heat conductor, cools the fins, and also abstracts heat fromthe water or brine in the system. The

liquid thus cooled becomes heavier than that in theuncooled portion ofthe system and a circulation will be started through the exchangerdownward and into the cooling chamber. Here the liquid will pick up heatfrom the articles inside, and'the liquid thus warmed will rise to thetop of the cooling coil and pass back to the top of the heat exchanger,thereby creatf ing a continuous circulation of liquid in the system. VThe drip of water from the tank is preferably adjusted to cover thefabric on the entire surface of the fins, and to supply just enough toallow for the evaporation.

In the hollow fin type of heat exchanger water from the system will seepthrough the holes in the fin walls and saturate the fabric. The pressurein the supply tank may then be regulated to supply just enough water tothe fabric.

While the temperaturev drop is dependent on the difference, betweenthewet and dry bulb readings of the thermometer, the amount of space thancan be lowered to the wet bulb temperature will depend on the area ofevaporative surface. AIarge space may be cooled by my invention with a,small heat exchanger because of the rapid evaporation and efficient heattransfer.

While the preferred form of my invention shows a blower to movethe air,it will be obvius that in localities where power is not avail-,refrigeration system able, any of the known may be used, such as flueing of funnels facing the as are used on ship board.

As an example, with an air temperature of with a humidity of 30 percent, the temperature of the refrigerator box may be reduced 20 and evenlower with lower humidities.

I claim:

1. A heat exchanger for a circulating refrigeration system whichcomprises a tube of high heat conducting material, a fin integral withsaid tube, a layer of fluid absorbent material on said fin, said finhaving ducts connecting said tube with said fluid absorbent material.

2. A' heat exchanger for a, circulating liquid which comprises a conduitof high heat conductivity, fins integral with said conduit extendinglongitudinally along said conduit, a layer of fluid absorbent materialon said fins, means for supplying a volatile fluid to said material, anenclosure for said conduit and fins, and means for passing a current ofair through said enclosure and between said fins in a direction oppositeto the circulation of liquid in said refrigeration system.

3. In combination with a circulating fluid refrigeration system, a heatexchanger comprising a tubular conduit for said fluid, fins on saidconduit, said conduit and said fins being formed of a metal having ahigh heat conductivity, a fluid absorbent material on the outer surfaceof said fins, said fins having apertures therein for conveying saidfluid to said fluid absorbent material.

4. In combination with a circulating fluid refrigeration system, a heatexchanger comprising a tubular conduit for said fluid having a smoothinterior duct and a corrugated external surface, said conduit beingformed of a, metal having high heat conductivity, a layer of liquidabsorbent material on said corrugated surface, and means for coolingsaid conduit by the evaporation of a volatile fluid from said liquidabsorbent material.

5. A heat exchanger for a circulating refrigeration system whichcomprises a tube of aluminum, an aluminum fin integral with said tube, alayer of fabric on said fin, said fin having ducts connecting theinterior of said tube with said fluid-absorbent material, and means forpassing a current of air through said fin to evaporate fluid therefrom,said ducts being of a size sufficient to supply fluid from the interiorof means of moving air action, or the providprevailing wind such thetube to said fabric at a rate at least equal I to the evaporation rate.

- EDWIN S. PRIDHAM.

